INTERDISCIPLINARY RESEARCH METHODS (IRM) CORE The IRM Core will ensure that CIRA science meets the highest methodological standards, and encourage innovative combinations and applications of methods from multiple disciplines. The Core will be organized in four teams to reflect the general areas of Core expertise and the methodological needs of CIRA scientists: Quantitative Methods and Biostatistics, Qualitative Methods and Ethnography, Cost Effectiveness and Mathematical Modeling and Biological Measures and Analysis. Each team will be led by a Co-Director, and will have staff to provide hands-on assistance with methods and analysis. Together, Core members have expertise in the design of basic social and behavioral research, structural intervention research, research combining biomedical and social-behavioral methods, research combining qualitative and quantitative methods, and research combining multiple levels of analysis. Through consultations required prior to submission of grant proposals and after successful grant award, as well as investigator initiated consultations at any point in the research process, the Core will advise CIRA scientists on these study designs as well as on issues in measurement and reliability, biostatistics, structural equation modeling, multi-level modeling, sampling, laboratory techniques, qualitative data coding, methods of qualitative data collection, methods of collecting cost data, and measuring and analyzing program costs. The Core also will provide assistance with a range of data analytic methods, expand and maintain a Measurement Resource File, provide centralized data backup and storage, create and maintain an HIV Database Archive, and develop multiple opportunities for methodological training. In addition the Core will encourage and contribute to methodological research.